病毒变异了？那会怎么样？

As the new coronavirus continues to spread around the globe, researchers say the virus is changing its genetic makeup slightly.

随着这种新型冠状病毒继续在全球范围内传播，研究人员表示，这种病毒的基因构成正在发生轻微的改变。

But does that mean it is becoming more dangerous to humans?

但这是否意味着它对人类的危害越来越大了呢?

And what would the impact be on any future vaccines?

这对未来的疫苗又有什么影响呢?

"In the literal sense of 'is it changing genetically,' the answer is absolutely yes," says Marc Lipsitch, an infectious disease epidemiologist at Harvard University.

哈佛大学传染病流行病学家马克·利普西奇表示:“从字面意义上讲，'这是否改变了基因呢’，答案绝对是肯定的。

"What is in question is whether there's been any change that's important to the course of disease or the transmissibility or other things that we as humans care about."

“值得讨论的是，是否有任何变化关乎于疾病的进程，传播能力或其他我们人类关心的事情呢。”

So far, "there is no credible evidence of a change in the biology of the virus either for better or for worse," says Lipsitch.

到目前为止，“还没有可靠的证据表明这种病毒的生物学变化是好是坏，”利普西奇说。

Coronaviruses — like all viruses — change small parts of their genetic code all the time.

冠状病毒和所有病毒一样，总是在改变着其遗传密码的一小部分。

"Viruses mutate naturally as part of their life cycle," says Ewan Harrison, scientific project manager for the COVID-19 Genomics UK Consortium, a new project that tracks the virus in the United Kingdom.

“病毒自然变异是它们生命周期的一部分，”COVID-19基因组英国联盟的科学项目经理伊万·哈里森说，COVID-19基因组英国联盟是一个跟踪英国病毒的新项目。

Like flu and measles, the coronavirus is an RNA virus.

与流感和麻疹一样，冠状病毒是一种RNA病毒。

It's a microscopic package of genetic instructions bundled in a protein shell.

它是包裹着蛋白质外壳的基因指令的微小包裹。

When a virus infects a person, the string of genetic instructions enables the virus to spread by telling it how to replicate once it enters a cell.

当一种病毒感染了一个人之后，一系列的遗传指令通过告诉病毒一旦进入细胞如何复制，从而使病毒得以传播。

The virus makes copies of itself and pushes them out to other cells in the body.

病毒会复制自身，并将它们推向体内的其他细胞。

Infectious doses of the virus can be coughed out in droplets and inhaled by others.

感染剂量的病毒可以通过飞沫咳出，也可以被其他人吸入。

Inevitably, viruses "make mistakes in their genomes" as they copy themselves, says Harrison.

哈里森说，病毒在复制自己的时候不可避免地“会在基因组中犯错误”。

Those changes can accumulate and carry over to future copies of the virus.

这些变化会积累并延续到病毒的未来副本。

Researchers are using these small, cumulative changes to trace the pathway of the virus through groups of people.

研究人员正在利用这些微小的、累积的变化来追踪病毒在人群中的传播途径。

So far, researchers who are tracking the genetic changes in SARS-CoV-2 — the official name for the coronavirus — say it seems relatively stable.

到目前为止，追踪SARS-CoV-2(冠状病毒的官方名称)基因变化的研究人员说，这种病毒似乎相对稳定。

It acquires about two mutations a month during this process of spread, Harrison says — about one-third to one-half the rate of the flu.

哈里森说，在传播的过程中，病毒一个月大约产生两种变异，速率大约是流感的三分之一到二分之一。

Coronaviruses differ from flu viruses in another key way that reduces the number of mutations.

冠状病毒与流感病毒的另一个关键区别在于它可以减少突变的数量。

They proofread their own genomes when they copy themselves, cutting out things that don't seem right.

当他们复制自己的时候，他们会校对自己的基因组，删除那些看起来不正确的东西。

"They maintain this ability to keep their genome pretty much intact," says Vineet Menachery, a virologist at the University of Texas Medical Branch.

德克萨斯大学医学分部的病毒学家文尼特·马娜切瑞说:“它们保持这种能力，以保持他们的基因组基本完整。”

"The mutations that they incorporate are relatively rare."

“它们发生结合的突变相对少见。”

This added proofreading function means that coronaviruses are also one of the largest RNA viruses.

这种附加的校对功能意味着冠状病毒也是最大的RNA病毒之一。

They're about 30,000 nucleotides long — double the size of flu viruses.

它们大约有3万个核苷酸长，是流感病毒的两倍。

But at 125 nanometers wide, they're still microscopic; 800 of them could fit in the width of a human hair.

但在125纳米宽时，它们仍然是微观的;800个病毒才相当于一根头发丝的宽度。

Nonetheless, their relatively larger size means "they have a lot more tools in their tool belt" compared with other RNA viruses, says Menachery — in other words, more capability of fighting off a host's immune system and making copies of themselves.

尽管如此，Menachery说，与其他RNA病毒相比，它们相对较大的体积意味着“它们的工具库带里有更多的工具”——换句话说，它们有更强的能力击退宿主的免疫系统并复制自己。

Researchers are on alert for changes that might affect how the coronavirus behaves in humans.

研究人员对可能影响人类冠状病毒行为的变化保持着警惕。

For instance, if the coronavirus developed ways to block parts of our immune system, it could hide out in our bodies and establish itself better.

例如，如果冠状病毒能够阻断我们免疫系统的某些部分，它就能隐藏在我们的身体里，更好地生存下去。

If it evolved to bind more strongly to human cells, it could enter them more efficiently and replicate more quickly.

如果它在进化过程中更强地与人类细胞结合，它就能更有效地进入人类细胞，并更快地进行复制。

But it's not as if the coronavirus needs to become more potent to survive and thrive.

但这并不是说冠状病毒需要变得更强才能生存和繁衍。

It's already replicating itself around the world very successfully, says Justin Bahl, an evolutionary biologist at the University of Georgia.

佐治亚大学的进化生物学家贾斯汀·巴尔说，它已经非常成功地在世界各地复制了自己。

"The viruses themselves are not actually under much pressure to change."

“实际上，病毒本身并没有面临太多改变的压力。”

Selective pressures could come from introducing treatments and vaccines that are effective against a narrow group of coronavirus strains.

选择性压力可能来自于引进对一小群冠状病毒株有效的治疗方法和疫苗。

If that happens, strains that aren't targeted by these measures would likely proliferate.

如果发生这种情况，那么这些措施没有针对的那些菌株可能就会扩散。

The small genetic changes that researchers have observed so far don't appear to be changing the function of the virus.

到目前为止，研究人员观察到的微小的基因变化似乎并没有改变病毒的功能。

"I don't think we're going to see major new traits, but I do think that we're going to see different variants emerge in the population," says Bahl.

“我认为我们不会看到主要的新特征，但我确实认为我们会在人群中看到不同的变异，”巴尔说。

And that slower rate of change is potentially good news for treatments and vaccines.

对于治疗和疫苗来说，变化的速度变慢可能是个好消息。

Researchers think that once a person gains immunity against SARS-CoV-2, either by recovering from an infection or by getting a future vaccine, they will likely be protected against the strains in circulation for "years rather than months," predicts Trevor Bedford, an evolutionary biologist at the Fred Hutchinson Cancer Research Center, in an assessment shared on Twitter.

研究人员认为,一个人一旦对SARS-CoV-2获得免疫力,比如从感染中恢复或接种了未来的疫苗,他们可能会在未来几年而不是几个月内，免受病毒传染的压力,”特雷弗贝德福德预言说,他是弗雷德哈钦森癌症研究中心的进化生物学家,在评估在推特上分享道。

Projects such as the COVID-19 Genomics UK Consortium will use these genetic drifts to track the path of the virus and figure out if there are hospitals or community hubs that are hot spots for contagion, according to Harrison.

哈里森说，COVID-19基因组英国联盟等项目将利用这些遗传漂移来跟踪病毒的路径，并查明是否有医院或社区中心是传染的热点。

This will give public health officials a sense of where and how the virus is being transmitted now.

这将使公共卫生官员了解到目前病毒的传播地点和方式。

Will the coronavirus surge when schools reopen?

校开学后新冠病毒会激增吗?

Will new strains emerge that develop resistance to drugs or vaccines that are introduced?

会不会出现对药物或疫苗产生耐药性的新毒株呢?

To answer such questions, Harrison says, the long-term plan is to track the virus in real time — and see how it changes as it spreads.

哈里森说，要回答这些问题，长期的计划就是实时追踪病毒，并观察病毒在传播过程中如何变化。

问题

文中提到跟感冒病毒相比，冠状病毒是更大还是更小呢？

留言回复正确答案，前十名朋友可以获得红包奖励哦，赶快来试试 吧！

感谢关注

跟amber一起看世界